Frank E Harrell Jr <[EMAIL PROTECTED]> [Sun, Jul 20, 2008 at 12:20:28AM CEST]: > Johannes Huesing wrote: >> Because regulatory bodies demand it? [...] > > And how anyway does this > relate to predictors in a model?
Not at all; you're correct. I was mixing the topic of this discussion up with another kind of silliness. I had a discussion with a biometrician in a pharmaceutical company though who stated that when you have only one df to spend it will be better to dichotomise it at a clinically meaningful point than to include it as a linear term. He kept the discussion on the ground of laboratory measurements like sodium, where a deviation from normal ranges is very significant (and unlike, say, cholesterol, where you have a gradual interpretation of the value). He has a point there, but in general the reason for sacrificing information is a mixture of laziness, the preference for presenting data in tables and to keep the modelling "consistent" with the tables (for instance to assign an odds ratio to each cell). -- Johannes Hüsing There is something fascinating about science. One gets such wholesale returns of conjecture mailto:[EMAIL PROTECTED] from such a trifling investment of fact. http://derwisch.wikidot.com (Mark Twain, "Life on the Mississippi") ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.